Steam oxidation of silicon, enhanced by arsenic or phosphorus doping at concentrations higher than 10(19) cm(-3), has been experimentally investigated in the temperature range of 700 to 900 degrees C on <100> and <111> surface orientations to gain better insight into the enhanced oxide growth and to derive data for possible model improvements. The redistribution of the dopant to the grown oxide, the transition layer, and remaining silicon is mathematically described. The resultant dopant concentration in the oxide and the associated dopant accumulation around the reacting surface follow exponential functions in agreement with measurement at least up to 800 degrees C oxidation temperature. The oxidation enhancement relative to lightly doped silicon clearly develops gradually with the oxide growth as do the oxide doping and the accumulation. Only 10 to 30% of the accumulated dopants reside in the silicon and contribute to conductivity there. However, there is an about 5 nm thick conductive layer above the regular silicon that can be etched off by HF but seems to change its structure with a rapid thermal annealing at 1000 degrees C, rendering it etch resistant.